Poor compression on '97 T5

zhenya · Post by **zhenya** » 31 Jul 2016, 08:08

Hey all. I was recently given back my '97 T5 that I sold to a family member several years ago. She's a bit worse for wear, but she didn't cost me anything and we could use the extra car if I can get it running well. I did a ton of work on this car in the years I owned it so it's overall worth saving. I drove it home 7 hours and other than a hole in the exhaust it ran fine - in fact it feels considerably more powerful and willing than my '98 AWD with a recent rebuild and only 120k total miles.

Last night I did a compression test just to see where things stand with 202k on the odometer. This car has always burned a small amount of oil from when I first owned it at 120k - usually a puff at start, especially when parked on a hill. I don't know what current consumption is as I haven't driven it many miles yet, but when I started it after sitting for several days yesterday there was no smoke at all. Previously I had gotten it down to a quart every couple thousand miles or so.

This test was done with a cold engine and dry only. I will re-test when I can warm and wet.

I got:
Cyl 1: 150
Cyl 2: 130
Cyl 3: 60
Cyl 4: 130
Cyl 5: 170

I presume given how well it runs that I'll see a difference when I re-run the test. Any comments or advice? I've never run a test wet before. Anything else I should consider before doing it again? I'm a bit surprised to see how low those numbers are considering how much power it still seems to make.

Post by **E Showell** » 31 Jul 2016, 10:01

Number 3 cylinder is a common location for a burned exhaust valve. I hate to be a pessimist, but you may be headed in that direction. A lot of folks have the actual burn occur while under load at high speeds going uphill. If memory serves, the area around Ithaca isn't exactly flat. Be careful on those hills.

zhenya · Post by **zhenya** » 31 Jul 2016, 14:01

I'm prepared for that as I've already been through it on the V70. Cylinder #3 as well - but that one was 180 on all other cylinders, and the car ran terribly with no power. This one still runs fine with excellent power, so I was a bit surprised to see this. I'll see if a bit of oil changes anything.

zhenya · Post by **zhenya** » 31 Jul 2016, 14:59

Well, good news, I think.

I ran the test again with a warm engine, but no oil in the cylinders. The numbers were

Cyl 1: 175
Cyl 2: 165
Cyl 3: 170
Cyl 4: 160
Cyl 5: 165

That feels a lot more about how this engine is running. So yesterday? Valve stuck slightly open? Stuck ring? Bad test (I repeated the bad cylinder a couple of times).

Hopefully I can delay any major engine work for a bit while I catch up on the cars' other needs.

Post by **Clemens** » 31 Jul 2016, 15:06

Maybe a sticking lifter? I have a lifzer tick sometimes after firing it up but that goes away after acter a few minutes. This could explain the 60 at cold, i believe.

Post by **abscate** » 31 Jul 2016, 16:28

Drive it and ignore that cold compression test.

Post by **mecheng** » 31 Jul 2016, 16:46

For the oil burn on a hill, try atp 205, I had the exact same problem, it cured it completely

zhenya · Post by **zhenya** » 31 Jul 2016, 17:12

Yeah, I'll continue to drive it and hope for the best. When I got the car I switched it to Mobil 1 high mileage and was able to work the consumption rate from ~1qt/800 miles to ~1qt every 2500 miles or so. I don't think my relative was using synthetic and it was down 1qt when I checked it before driving home, so we'll see what the rate is now. I may try the atp 205 if it's bad. I suspect it is just concentrated additives like the high mileage oils also have?